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Activity 1: Breeding Bunnies
In this activity, you will examine natural selection in a small population of wild rabbits. Evolution,
on a genetic level, is a change in the frequency of alleles in a population over a period of time.
Breeders of rabbits have long been familiar with a variety of genetic traits that affect the
survivability of rabbits in the wild, as well as in breeding populations. One such trait is the trait
for furless rabbits (naked bunnies). This trait was first discovered in England by W.E. Castle in
1933. The furless rabbit is rarely found in the wild because the cold English winters are a
definite selective force against it.
Note: In this lab, the dominant allele for normal fur is represented by F and the recessive allele
for no fur is represented by f. Bunnies that inherit two F alleles or one F and one f allele have
fur, while bunnies that inherit two f’s have no fur.
• Breeding Bunnies: Gene Frequency Data form (pdF)
• Breeding Bunnies: Discussion Questions (pdf)
• 50 red beans
• 50 white beans
• 1 paper bag or deep bowl
• 3 dishes or containers
• labels
• pens
1. Answer the questions on the Gene Frequency Data Sheet, fill in the hypothesis section and
specific predictions based on that hypothesis.
2. Get into your assigned group and gather the needed materials to complete the lab. If you are
working alone, proceed on your own.
3. The red beans represent the allele for fur, and the white beans represent the allele for no
fur. The container represents the English countryside, where the rabbits randomly mate.
4. Label one dish FF for the homozygous dominant genotype. Label a second dish Ff for the
heterozygous condition. Label the third dish ff for those rabbits with the homozygous
recessive genotype.
5. Place the 50 red and 50 white beans (alleles) in the container and shake up (mate) the rabbits.
(Please note that these frequencies have been chosen arbitrarily for this activity.)
6. Without looking at the beans, select two at a time, and record the results on the data form
next to "Generation 1." For instance, if you draw one red and one white bean, place a mark in
the chart under "Number of Ff individuals." Continue drawing pairs of beans and recording the
results in your chart until all beans have been selected and sorted. Place the "rabbits" into the
appropriate dish: FF, Ff, or ff. (Please note that the total number of individuals will be half
the total number of beans because each rabbit requires two alleles – 1 from mom and 1 from
7. The ff bunnies are born furless. The cold weather kills them before they reach reproductive
age, so they can't pass on their genes. Place the beans from the ff container aside before
beginning the next round.
8. Count the F and f alleles (beans) that were placed in each of the "furred rabbit" dishes in the
first round and record the number in the chart in the columns labeled "Number of F Alleles"
and "Number of f Alleles." (This time you are really counting each bean, but don't count the
alleles of the ff bunnies because they are no longer in the gene pool because these rabbits
died before they could reproduce.) Total the number of F alleles and f alleles for the first
generation and record this number in the column labeled "Total Number of Alleles."
9. Place the alleles of the surviving rabbits (which have grown, survived and reached
reproductive age) back into the container and mate them again to get the next generation.
10. Repeat steps five through nine to obtain generations two through ten. If working as a team,
make sure everyone in your group has a chance to either select the beans or record the
11. Determine the gene frequency of F and f for each generation and record them in the chart in
the columns labeled "Gene Frequency F" and "Gene Frequency f." To find the gene frequency
of F, divide the number of F by the total, and to find the gene frequency of f, divide the
number of f by the total. Express results in decimal form. The sum of the frequency of F and
f should equal one for each generation.
12. Record your group’s frequencies so your classmates can see them.
13. Graph your frequencies. Prepare a graph with the horizontal axis as the generation and the
vertical axis as the frequency in decimals. Plot all frequencies on one graph. First, plot your
own data. Use a solid line for F and a dashed line for f. Then, plot the class totals. Use the
same symbols for each group but a different color.
14. Complete the Discussion Questions form with your group.
15. Each student will turn in a Gene Frequency Data Sheet, two graphs: 1) group data and 2) the
class data, and the answers to the discussion questions.
Name: __________________________________ Date:_________________ Period:____
Breeding Bunnies: Gene Frequency Data
How does natural selection affect gene frequency over several generations?
Come up with a hypothesis about what will happen with the breeding bunnies with fur and the
naked bunnies?
Write what you would predict (if your hypothesis is true, then….) about the frequency of F alleles
and f alleles in the population of rabbits after 10 generations, where ff bunnies are selected
Number of
Number of
Number of
Number of
Number of
Gene Freq.
Adapted from PBS
Gene Freq.
1. What was your original hypothesis?
2. Based on your lab data, do you need to change your hypothesis? Explain.
3. Compare the number of alleles for the dominant characteristics with the number of
alleles for the recessive characteristic
4. Compare the frequencies of the dominant allele to the frequencies of the recessive
5. In a real rabbit habitat new animals often come into the habitat (Immigrate), and
others leave the area (emigrate). How might emigration and immigration affect the
gene frequency of F and f in this population of rabbits? How might you simulate this
effect if you were to repeat this activity?
6. How do your results compare with the class data? If significantly different, why are
they different?
7. How are the results of this simulation an example of evolution?